[mesa-users] Asplund abundances in MESA -- which ones?

Stan Woosley woosley at ucolick.org
Wed Apr 15 10:58:36 EDT 2015


Unless you are explicitly interested in modeling the current solar convection zone, the abundance of Li
there is useless. It has been depleted orders of magnitude by nuclear reactions at the base of the convection
zone. The meteoritic value - from primitive C1 carbonaceous meteorites - reflects the composition of the 
primordial solar nebula.

Also, if you are interested in solar composition as a representation of initial Pop I material
in making a star model, or as a target for nucleosynthesis studies, you should use the corrected
protosolar abundances not the current solar photospheric ones. Diffusion out of the convection
zone has changed the abundance of everything, including H and He. I recall the change in 
heavy elements as being 0.05 dex.

Lodders (2009) has a similar - and for me - equally useful solar and zero age solar abundance set.

Reading wither of their papers gives background on the uncertainties in each element.

Stan



On Apr 15, 2015, at 6:20 AM, Richard Townsend <townsend at astro.wisc.edu> wrote:

> Thanks, Jieun!
> 
> Comparing the data in chem_def.f90 against Table 1 of Asplund+09, it looks like the meteoritic values for As, Se and Br are used in the file because the photosphere values are missing.
> 
> However, that doesn’t explain why the meteoritic value for Li is used, rather than the photosphere value. Does anyone have any ideas?
> 
> cheers,
> 
> Rich
> 
>> On Apr 14, 2015, at 9:52 PM, Choi, Jieun <jieun.choi at cfa.harvard.edu> wrote:
>> 
>> Hi Rich,
>> 
>> Comparing Table 1 in Asplund+09 and the log abundances listed in init_AGSS09_data, it looks like MESA's using present-day photosphere values with a few exceptions, e.g., Li, Br.
>> 
>> Cheers,
>> Jieun
>> 
>> On Tue, Apr 14, 2015 at 9:37 PM, Richard Townsend <townsend at astro.wisc.edu> wrote:
>> Hi folks —
>> 
>> In chem/chem_def.f90, the ‘AGSS09' abundances are referenced as coming from Asplund, Grevesse, Sauval, and Scott 2009 (Annu. Rev. Astron. Astrophys. 2009. 47:481–522). But Asplund et al give values for both solar and proto-solar abundances. Which is MESA using?
>> 
>> cheers,
>> 
>> Rich
>> 
>> 
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